1) Field of the Invention
The present invention relates to a monitoring system for semiconductor device fabrication facilities, and more particularly, to a monitoring system for semiconductor device fabrication facilities for simplifying the line installment between each facility and the monitoring system by providing a certain frequency to each facility to carry out a corresponding fabrication process of semiconductor devices and a measurement process therefor, and using one information transmission line and selective signal line.
2) Description of the Related Art
Generally, a certain pattern is formed on a semiconductor wafer through an array of processing steps such as oxidation, diffusion, etching, deposition, or ion-implantation, and semiconductor devices are manufactured via an assembly process. Between the above processing steps, or during a certain processing step, various kinds of analysis, inspection, or measurement is performed on wafers or chips.
Each analyzing step or measuring step for a certain process is carried out on its corresponding fabrication facility, and so, several and various kinds of fabrication facilities are provided on the semiconductor device fabrication factory.
In order to produce normal semiconductor devices, it is necessary to check the operational state of the process carried out in each fabrication facility, or the state of the facility itself every process time, and so, in case of an abnormal operational state being found, proper and quick action should be made. One embodiment of the monitoring systems for the above purpose is disclosed in U.S. patent Ser. No. 5,568,042, entitled "Monitoring And Control of Filter In A Power Network."
Meanwhile, the malfunctioning process or facility abnormality is checked using various kinds of sensors installed in the corresponding semiconductor device fabrication facility, and in case of a process malfunction or facility abnormality, a corresponding sensor senses and outputs the sensing signal responsive thereto.
The sensing signal is applied to an alarming means for alerting an operator at work, or is transferred to a central monitoring apparatus for providing a judgment regarding the operational state of a corresponding process remotely. In order to transfer the sensing signal to the central monitoring apparatus, the central monitoring apparatus and the semiconductor device fabrication facility should be interfaced.
As shown in FIG. 1, for remote-monitoring, the central monitoring apparatus 10 is connected to each semiconductor device fabrication facility 12 to 18 to receive the sensing signals.
The conventional central monitoring apparatus 10 is individually connected to each semiconductor device fabrication facility 12 to 18, that is, with an independent line distribution.
For the interface between the central monitoring apparatus 10 and each semiconductor device fabrication facility, a pair of inner lines are necessary for the formation of an electrical loop. That is, the number of the lines formed with a pair of inner lines is the same as the number of the semiconductor device fabrication facilities connected to the central monitoring apparatus 10. Therefore, more semiconductor device fabrication facilities to be monitored require more lines connected to the central monitoring apparatus which is connected to each facility on a one-to-one basis. As a result, the total length of the lines is longer and more complicated, thereby increasing the installment expenses and the difficulties of the layout inside the fabrication factory. Further, the control and the management of the lines become more difficult.